Abstract

High-entropy boride ceramics have attracted increasing attention for high-temperature applications owing to their exceptional hardness and thermal stability; however, their low fracture toughness and poor tribological performance limit practical use in extreme environments. In this work, high-entropy boride-silicon carbide whisker (HEB-SiCw) composite ceramics were fabricated by introducing SiC whiskers into (Ti0.2Zr0.2Nb0.2-Mo0.2Ta0.2)B2 via boro-carbothermal reduction and spark plasma sintering. The influence of SiCw morphology ( B6 and B7 types) and content (5, 10, 20, and 30 wt%) on the microstructure, mechanical behavior, and high-temperature tribological performance was systematically investigated. The incorporation of SiCw refined the grain structure and improved fracture toughness through crack deflection, whisker bridging, and pull-out mechanisms. The optimal composite containing 20 wt% B7 SiCw achieved a fracture toughness of 7.72 +/- 0.24 MPa & sdot;m1/2 and a flexural strength of 691 +/- 38 MPa. Tribological tests from room temperature to 800 degrees C revealed a transition in wear mechanisms from mild oxidative to adhesive-oxidative wear and finally to oxidative wear accompanied by self-lubrication. At 800 degrees C, the in-situ formation of amorphous SiO2 and a little layered MoO3 lubricating films reduced the coefficient of friction by 40 % and the wear rate by 78 % compared with the unreinforced HEB. These findings demonstrate that SiCw reinforcement provides synergistic toughening and self-lubricating effects, offering a promising design strategy for high-entropy boride ceramics used in extreme-temperature friction environments.

Keywords Plus: MECHANICAL-PROPERTIES，PHASE

Published in TRIBOLOGY INTERNATIONAL，Volume217；10.1016/j.triboint.2025.111624，MAY 2026